NASA IXO Mission Concept IXO Mission Concept ... Cards Level-3: Spacecraft Modules . IXO Science Mtg / January 28, ... 4.1 Hz Mast Torsion 1.8 Hz Mast Bending

NASA IXO Mission Concept Jean Grady / GSFC IXO NASA Project Manager

IXO Science Meeting/ January 28, 2009 Goddard Space Flight Center

IXO Science Mtg / January 28, 2009 Mission Concept-2

Timeline for IXO Mission Concept Development

  Pre-IXO Mission Studies laid foundation for IXO mission concept development

–  Con-X mission studies, mirror and instrument definition, etc. (1998 – 2008) –  Large extensible bench studies (2004)

  Preliminary concept studies for single telescope observatory with extensible bench: 3/08 – 7/08

  ESA and NASA HQ agree on mission study scope: 7/08   Mission Design Lab study at NASA/GSFC: 7/08   IXO Science Team Meetings: 8/08 (GSFC); 9/08 (MPE)   IXO Coordination Group defines instrument set: 11/09   Refine and add detail to mission concept: 10/09 – 1/09

–  Payload accommodation update to include all instruments (11/08 – 1/09) –  Integrated modeling (10/08 – 1/09) –  NASA Mission Design Lab study update to systems/subsystems (1/09)


Mission Overview

  Single Mirror Configuration –  3.4 m dia mirror with a 20 m focal length

–  Part of the metering structure is extensible

  Mission Life and Sizing –  Class B Mission: no performance

degradation w/ single point failure

–  Mission Life: 5 years required; consumables sized for 10 years

  Launch and Orbit Insertion –  Launch on an Atlas V 551 medium fairing or

Ariane 5 in 2020

–  Observatory Dry Mass is ~6100 kg (w/ 30% contingency) within capability of Atlas V or Ariane 5

–  Direct launch into “zero Insertion delta-v” L2 orbit

–  100 day cruise

  Mission Orbit –  L2 800,000 km semi-major axis halo orbit

Earth- L2 Distance 1.5 x 106 km

L2

Lunar Orbit

E

Earth-Sun angle between 7 and 34º

Max Range 1.8 x 106 km

L2 Orbit ~800,000 km radius, ~180 day period

L2 Transfer Trajectory

To Sun

Courtesy - JWST


IXO Payload

  Flight Mirror Assembly (FMA)

–  Highly nested grazing incidence optics

  Instruments

–  X-ray Micro-calorimeter Spectrometer (XMS)

–  X-ray Grating Spectrometer (XGS)

–  Wide Field Imager (WFI) and Hard X-ray Imager (HXI)

–  X-ray Polarimeter (X-POL)

–  High Time Resolution Spectrometer (HTRS)

  XMS, WFI/HXI, XPOL and HTRS observe one at a time by being inserted into focal plane via a Moveable Instrument Platform (MIP)

–  4 Science Operational Modes

–  XGS always operational

Flight Mirror Assembly

XMS

Representative Gratings

WFI/HXI

Moveable Instrument Platform (MIP)

~ 3 m

HTRS

XPOL

20 m


Science Modes

Mode 1 Mode 2 Mode 3 Mode 4

Instrument Operations

Science XMS, XGS WFI, HXI, XGS X-Pol, XGS HTRS, XGS

Standby WFI, HXI, X-Pol, HTRS

XMS, X-Pol, HTRS

WFI, HXI, HTRS, XMS

WFI, HXI, XMS, X-Pol

Percent time for each Mode 40% 40% 10% 10%

Observation Duration (hours)

Average 10 hours

Minimum 30 minutes

Peak 48 hours

Instrument Operation/Science Mode Summary

  4 Science Modes defined –  One Science Mode for each instrument location on Movable Instrument

Platform (MIP)

–  XGS operates during all Science Modes

–  Instruments that are not conducting science are in placed in Standby


Payload Mass, Power, and Data Rate Summary

  Driving Power Science Mode: –  Mode 1 (XMS + XGS) is ~2000 average; ~2100 W peak (including FMA heater power)

  Driving Data Science Modes: –  Mode 2 (WFI/HXI +XGS) is ~3500 kbps peak –  Mode 3 (X-POL+ XGS) is ~450 kbps ave

  Data Storage Sized for 12 hours of peak plus 60 hours of average data (assuming one missed pass)

  Downlink sized to accommodate 2 bright source peak observations (48 hours) per month and meet 72 hour latency on average observations


Deployment Module

Instrument Module

Spacecraft Module

Optics Module

12.1 m

Deployed IXO Configuration

Stowed IXO Configuration

NASA Mission Design

10.1 m


Observatory Module Overview

  Deployment Module –  3.9 m diameter shroud –  Extensible ADAM-type

masts (3) with harness (not shown

–  Two X-ray baffles (not shown)

  Instrument Module –  Sunshade –  Moveable Instrument Platform (MIP)

w/ XMS, WFI/HXI, X-POL, HTRS –  Fixed Instrument Platform (FIP)

w/ XGS camera

  Spacecraft Module –  9-sided Bus w/ avionics, power

system electronics, battery, propulsion tanks, reaction wheels, etc.

–  Ka- and S-band High Gain Antenna –  Composite isogrid metering

structure –  Body mounted solar array

(not shown) –  Ultraflex solar arrays (3.4 m dia) –  Thrusters (14)

  Optics Module –  Flight Mirror Assembly (FMA) –  FMA deployable covers –  Deployable Sunshade


Instrument Module

  XPOL, XMS, WFI/HXI, & HTRS detectors and proximity electronics mount on Moveable Instrument Platform (MIP)

  XGS camera mounts to the Fixed Instrument Platform (FIP)

  Remote instrument boxes mount to the underside of the FIP

  Radiators, VCHPs (variable conductance heat pipes), blankets, heaters on MIP and FIP provide thermal control

  Single Remote Interface Unit on the FIP for instrument command and data interface to spacecraft C&DH, and power distribution

  Large “common instrument baffle” for on-axis instruments on MIP


Instrument Module

XGS Camera

Radiator

Fixed Instrument Platform (FIP)

Radiator

Launch Lock Mechanisms (6)

X-Ray Polarimeter

XMS

WFI/HXI

HTRS

Sunshade


XPOL

Instrument Suite Layout

XGS CCD Camera

WFI / HXI

HTRS

XMS (Shown at focus)

Instrument Proximity Electronics (10)

MIP rotation range 133 degrees


Deployment Module   3 ADAM masts deploy the IM,

shroud, baffles and harness –  Provides on-orbit alignment

stability between optics and detectors

–  First modes: 1.8 Hz bending and 4.1 Hz torsion

–  Proven technology –  Mast and harness stows into

canister

  Shroud blocks light and supports baffles

–  Accordion-pleated multi-layer insulation blanket assemblies

–  Two concentric blanket assemblies form a “Whipple shield” to minimize micrometeorite penetrations

–  Stows in channel on top of the spacecraft bus

10 cm

12.1 m

Shroud stowage channel

ADAM Mast (3)

Concentric MLI blankets In Stowage Channel

Stowed Configuration

Baffle (2) Deployed Configuration


X-ray Trace

  The X-ray traces of the FMA and XGS traverse nearly the entire length of the observatory

  Either Critical Angle Transmission Grating (CATG) or Off-Plane Grating (OPG) XGS can be accommodated

  The x-ray beams drive the size, shape and placement of the spacecraft bus “ring”

–  Needs to be forward of the FMA for sufficient volume for bus components

–  Distance between the bus and the FMA limited to fit in the Atlas V 5 medium fairing

–  (CG, mass propellant lines are additional considerations)

CATG XGS OPG XGS

6.4 m


Spacecraft Module Overview

  GN&C –  Pointing Requirements: 10 arcsec control, 1

arcssec knowledge, 0.2 arcsec jitter –  AST-301 star trackers (2), HR-16 reaction

wheels (5), Course and Fine Digital Sun Sensors, IRU, Distributed Telescope Aspect Determination System (TADS)

–  Solar Pressure Torque @ 1.5m CM/CP offset compensated with 0.9 N monoprop pulse every ~18 minutes

  Propulsion –  NTO/Hz Bi-prop pressure regulated –  Tanks sized for 10 years+; placed to minimize

CG migration over life of mission –  22 N thrusters (16), 0.9 N thrusters (2)

  Electrical Power –  19.5 m2 Solar Array for 5000 W (Beginning of

Life) •  Body mounted solar array allows for indefinite safe mode

•  Ultra-flex deployable arrays help reducing Center of Mass-Center of Pressure offset

–  S/A output routed to PSE for regulated 28V DC –  50 AH LiIon battery sized for Launch only –  Electrically independent FMA power system

for thermal control

2.35 m dia hole

ADAM Canisters (3) Reaction wheels (5)

Helium pressurant

tank

Sun Side

Avionics

~4.0 m dia

Anti Sun Side

NTO Tank (2)

Hydrazine Tank (2)

Deployable Solar Array (2)

Body Mounted

Solar Array

Composite Isogrid Fixed Metering

Structure

High Gain Antenna


Spacecraft Module Overview (cont.)   C&DH

–  Networked highly redundant Spacewire architecture

–  400 Gbit storage

–  BAE RAD 750 SBC (6U) processor

  Flight Software –  C&DH/FSW provides:

•  Commands and time distribution

•  ACE and PSE functions (no separate ACE, PSE)

•  Mechanisms control

–  Instruments provide any data compression, packetization and time stamping

–  Re-use of existing C&DH FSW

  RF Communication –  Ka-band for science data and TT&C via gimbaled

HGA to Deep Space Network 34 meter antenna

–  S-band for TT&C via HGA to DSN 34 meter, via omni to DSN 34m, and via omni to TDRSS for launch/LEO critical events

–  Contacts: one 30 minute contact/day nominal; 3 hr contact twice/month for peak data; Two contacts / day during Cruise

–  Observe/range/orbit determination during downlink

Level-2: Obs. Module Functions

Level-4: Sub-Ass’y/Cards

Level-1: Mission

Level-3: Spacecraft Modules


NASA FMA Concept

  Key requirements: –  Effective area /Resolution:

•  ~3 m2 @ 1.25 keV; 0.65 m2 @ 6 keV with 5 arcsec angular resolution

•  ~150 m2 @30 keV with 30 arcsec ang. res.

  Overall dimensions: 3.4 m dia x 0.8 m   Segmented Wolter I optical design   Slumped glass mirror segments   60 modules: 24 outer, 24 middle, 12 inner   60 mirror modules each with

200-300 segments   Hard X-ray mirror module, with multi-layer

coated mirrors, in the center provides high energy response

  Total FMA mass is ~1750 kg (current best estimate, no contingency)

  Power is ~1400 W to maintain 20 C   Finite Element Analyses support design

concept

Thermal Pre-Collimator

Stray Light Baffle

Module

FMA Structure

Spacecraft Interface

Finite Element Model of FMA Structure


Flight Mirror Assembly (FMA)

FMA interior and exterior covers not shown

Deployable Sun Shade

Spacecraft Adapter

L.V. Separation System

Optics Module


Mechanical

Initial Integrated Modeling Supports Configuration

4.1 Hz Mast Torsion

1.8 Hz Mast Bending

Mechanical

Decenter Requirement < .02 mm

Defocus Requirement < .25 mm

Thermal

Jitter 1.8 Hz

14.1 Hz


I&T S/C bus “ring” components onto structure and test

Integrate OM onto SM/DM/

IM

Observatory environmental

testing

Integrate IM onto

SM/DM

Integrate fixed metering structure,

propulsion lines, solar arrays, thermal, etc

Integrate DM with SC

and test

Integrate Deployment mechanisms with Shroud and test

Integrate instruments into IM

Integrate FMA, covers, s/c adaptor sunshade, etc

•  Vibration •  Acoustic •  TV & T/B •  Alignment •  Func. I&T

Integrate IM support equipment (structures, mechanisms,

harness, RIU’s, PDU’s, etc. )

•  Bakeout •  Mechanism functional

DRAFT IXO High Level I&T Flow

Deployment Module (DM)

•  Instrument Cals •  TV/TB •  EMI/EMC •  Func. I&T •  Vibration

Instrument Module (IM)

Optics Module (OM)

•  TV/TB •  EMI/EMC •  Acoustics •  Shock •  Mass

properties •  Magnetics

•  Alignment •  Functional test •  Comp. perf.

test •  Ops testing •  Inst. cross cal

S/C Module (SM) Observatory I & T

Etc…

•  RF Testing •  Maint. Cals •  Verify Optical

Path •  Deployments

•  Func. I&T •  Vibration

•  Functional I&T •  Vibration


DRAFT Mission Schedule


Next Steps Preparing for Decadal

  Finalize observatory system & subsystem updates from MDL: 1/09 – 2/09 –  Observatory system & subsystem updates from MDL

  Update Payload Definition Document: 1/09 input – 2/09 draft – 3/09 final

  Update Technology assessments and plans: 2/09 draft – 3/09 final

  Perform Independent Cost and Schedule Estimates: 2/09 – 4/09

  Receive Request for Information (RFI) from Decadal: 2/09

  Prepare and submit RFI response: 2/09 – 3/09

  Receive Request for Programmatic Information from Decadal: 4/09

  Prepare/submit Mission Programmatic response to Decadal: 4/09 – 5/09 –  Cost and schedules to be reviewed by NASA HQ prior to submittal

  Mission presentations to Decadal: 6/09

Documents

NASA IXO Mission Concept IXO Mission Concept ... Cards Level-3: Spacecraft Modules . IXO Science Mtg / January 28, ... 4.1 Hz Mast Torsion 1.8 Hz Mast Bending